Bubble Boy and Berlin Patient

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Two examples of stem cell therapies have made history: the cure of X-SCID-affected Jack Crick and the cure of the Berlin patient who, with the help of stem cells, escaped both HIV and leukemia . His case, however, has remained a highly regarded individual case to this day. Both patient stories are interesting against the background that they embody the future potential and the associated hope in stem cell therapy - but still represent the exceptional situation.

Patient Jack Crick

2004Born in May
2004X-SCID is diagnosed in September. The search for a suitable bone marrow donor unsuccessful. Gene therapy using the patient's own blood stem cells is successful, even without chemotherapy.
2011Patient has had no symptoms since.

Attending PhysicianBobby Gaspar, Great Osmond Street Hospital, London

X-SCID

SCID stands for severe combined immunodeficiency;

A weakening of the immune system due to the absence or lack of lymphocyte function; mutations in genetic information (DNA) cause the disruption of T cell development. The patients' immune systems cannot cope with the pathogens in our normal environment and the affected children must therefore live in a sterile environment.

Therapy

Collection of hematopoietic stem cells (CD34-positive); inserting the corrected gene into the test tube using a retroviral vector (taken from the mouse leukemia virus); stem cells are returned to the patient.

Advantages: Use of own cells instead of foreign cells; low risk of rejection or incompatibility; no suitable donor necessary.

DiscussionThe introduction of a new gene can lead to changes in cell properties or to degeneration (cancer). Cases are known where patients developed leukemia. The trigger seems to be the retroviral vector. Research is being carried out on the use of newer HIV-derived lentiviral vectors, for example, which have a much better safety profile.

TherapyTransplantation of allogeneic stem cell transplantation of a donor with a mutation in the cell surface receptor CCR5. The mutation prevents the HI virus from entering the cells.

DiscussionIt is not clear whether this individual case is reproducible. The procedure is very expensive. In 2012, Steven Yukl (University of California, San Francisco) investigated nine billion patient blood cells using polymerase chain reaction (PCR). After several attempts he identifies fragments of the virus genome in the blood plasma. Douglas Richman (University of California, San Diego) also conducts blood tests and finds no residues. He considers contamination in the Yukl test possible; in addition, PCR is highly sensitive and error-prone.